It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Holy Prophet (peace and blessings of Allah be upon him) said: Any prayer in which Surah Al-Fatiha is not recited is incomplete, incomplete.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7901
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن، م: 395.